5-((E)-2-((2S,4R)-4-hydroxy-6-oxotetrahydro-2H-pyran-2-yl)vinyl)-4-(4-fluorophenyl)-6-isopropyl-2-(N-methylmethanesulfonylamino)pyrimidine (rosuvastatin lactone—RSVL) is a possible key intermediate in the synthesis of rosuvastatin and its pharmaceutically acceptable salts. Rosuvastatin calcium, chemically described as bis[(3R,5S,E)-7-(4-(4-fluorophenyl)-6-isopropyl-2-(N-methylmethylsulfonamido)pyrimidin-5-yl)-3,5-dihydroxyhept-6-enoic acid] calcium salt, is a synthetic lipid-lowering agent that acts as an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase inhibitor). HMG-CoA reductase inhibitors are commonly referred to as “statins.” Statins are therapeutically effective drugs used for reducing low density lipoprotein (LDL) particle concentration in the blood stream of patients at risk for cardiovascular disease. Therefore, rosuvastatin calcium is used in the treatment of hypercholesterolemia and mixed dyslipidemia.
Rosuvastatin and the synthesis of rosuvastatin calcium was first disclosed in EP 521471 A1; in the last two steps of the whole synthesis provided by hydrolysis of methyl ester of rosuvastatin (methyl rosuvastatin) in polar solvent, e.g. ethanol, in the presence of a base, following by isolation of sodium salt of rosuvastatin (sodium rosuvastatin) and converting said sodium salt of rosuvastatin with a water soluble calcium salt under aqueous conditions to calcium salt of rosuvastatin.
International patent application WO 2004/052867 A1 describes the preparation of rosuvastatin using rosuvastatin lactone as an intermediate. Rosuvastatin lactone is isolated from toluene solution by evaporation of solvent.
International patent application WO 2005/040134 A1 discloses rosuvastatin lactone as a precipitated solid from hexane and its use for preparation of amorphous rosuvastatin calcium via rosuvastatin lactone.
International applications WO 2007/039287 A1 and WO 2008/119810 A2 describe the synthesis of rosuvastatin via 5-((E)-2-(2S,4R)-4-(tert-butyldimethylsilyloxy)-6-oxotetrahydro-2H-pyran-2-yl)vinyl)-4-(4-fluorophenyl)-6-isopropyl-2-(N-methylmethanesulfonylamino) pyrimidine (RSVLTBS). RSVLTBS is isolated as a white amorphous solid.
The object of the present invention is to provide an improved process for preparing 5-((E)-2-((2S,4R)-4-hydroxy-6-oxotetrahydro-2H-pyran-2-yl)vinyl)-4-(4-fluorophenyl)-6-isopropyl-2-(N-methylmethanesulfonylamino)pyrimidine (rosuvastatin lactone—RSVL) and a process for preparing crystalline 5-((E)-2-((2S,4R)-4-(tert-butyldimethylsilyloxy)-6-oxotetrahydro-2H-pyran-2-yl)vinyl)-4-(4-fluorophenyl)-6-isopropyl-2-(N-methylmethanesulfonylamino)pyrimidine (RSVLTBS), so as to provide valuable intermediates for the preparation of rosuvastatin and pharmaceutically acceptable salts thereof.